Polishing machine



1944- I e. E. HULBERT ET AL 2,341,442

POLISHING MACHINE Filed March 25, 1941 2 Sheets-Sheet l GEORGE EH04 BER T HEEEEH 715. fA/DGE e .1944. G. E. HULBERT ETAL 2,341,442

POLISHING MACHINE Filed March 25, 1941 2 Sheets-Sheet 2 GEORGE EH04 557-? 7" HEREER TSINDEE Patented Feb. 8, 1944 POLISHING MACHINE George E. Hulbcrt and Herbert S. Indge, Westboro, Mass, assignors to Norton Company, Worcester, Mass, a corporation of Massachusetts Application March 25, 1941, Serial No. 385,086

' (o1. l--1i5) 3 Claims.

The invention relates to polishing, lapping and surface finishing machines.

One object of the invention is to provide a machine of the character indicated particularly adapted to finish the conical surfaces of piston rings. Another object of the invention is to provide a piston ring finishing machine. Another object of the invention is to provide a machine for polishing, lapping or finishing a conical surface or part thereof.

Another object of the invention is to provide a belt abrader for the polishing of annular members of different shapes. Other objects will be in part obvious or in part pointed out hereinafter.

The invention accordingly consists in the features of construction, combinations of elements, and arrangements of parts, aswill be illustrative- -1y described herein, and the scope of the application of which will be indicated in the following claims.

In the accompanying drawings showing one of many possible embodiments of the mechanical features of this invention,

Figure 1 is a perspective view of a machine constructed in accordance with the invention;

Figure 2 is a View, partly in side elevation and partly in section, illustrating the polishing belt in contact with a work piece, the shoes which hold it in contact, and the means for resiliently urging the shoes against the belt;

Figure 3 is a vertical cross-sectional view of the machine, taken just behind the belt; and

Figure 4 is a fragmentary plan view of the machine showing locating stops for the tool slide.

It has recently become thepractice to make piston rings for airplane engines of the shape indicated by the piston ring 9 in Figure 2. We do not deem it necessary to go into the reason for making piston rings in this shape, since whatever the reason it becomes a problem of the manufacturer of polishing, lapping and surface finishing machinery to provide a machine to finish such rings. It happens that the airplane manufacturers are quite particular about surface finish of the conical surfaces of these piston rings which are located in the ring grooves of the pistons. Accordingly for producing an excellent finish upon these conical surfaces, We provide a machine which we will now describe.

Referring first to Figure l, the machine has a suitable base It roughly in the form of an inverted U. In one leg of the U is a motor H driving a. pulley l2 and thereby through the medium of a belt l3 driving a, pulley M in aheadstock E5. The headstock. I5 is mounted on ways l6, 16 extending the entire length of the base Ill on the top thereof. J ournalled in the headstock I5 is a spindle H to the front end of which is fastened a jaw chuck IQ of usual construction which grips the Work piece piston ring 9.

Likewise mounted to slide on the ways It, I 6 is a tool slide 20. This tool slide 25 has an upwardly extending standard 21 located at the rear of the machine. Extending forwardly from the standard 2! is a post 22 on the front end of which is mounted a pulley 23 journalled upon a stud 24. Referring to Figures 1 and 3, extending forwardly from-the standard 2| at the top thereof is a hollow post 28 through which extends a shaft 29 journalled in the bearings 38 and 3!, The shaft 29 is the armature shaft of a motor 32 supported, on a bracket 33 fastened to the back of the standard 2|. To the front of the shaft 29 is fastened a driving pulley 34.

Formed integral with the tool slide 20 and with the standard 2! is a depending support 35. Extending forwardly from the bottom of the depending support 35 under the top part of the inverted U of the base H! is a post 38 in which is fastened a stud 3'! which journals a pulley 38. The post 22 is shown as integral with the standard 2| and is hollow while the post 36 is shown as fastened to the depending support 35 by bolts 4!] located in slots M in a base 62 of the post 36. While such details can be varied within wide limits, it is desirable that at least one of the posts 22, 28 or 36 be adjustable to tension an abrasive belt 45 which passes around the pulleys 23, 34 and 38. The abrasive belt it does the polishing. Its base may be either paper or cloth or other flexible substance and the abrasive may be of any suitable type, such as emery, fused alumina, corundum, silicon carbide, boron carbide, or diamonds. The bond may be glue or one of the synthetic resins, such as phenol formaldehyde, glyptal or of any other desired type. By energizing the motor 32, the abrasive belt is caused to travel in contact with a rotating piston ring 9, thereby polishing its surface. The belt 45 passes through a slot 46 in the tool slide 28 and through a wide opening ll extending the length of the upper part of the inverted U of the base Iii.

We further provide means for holding the belt 45 in contact with the surface to be polished with an even pressure. As best disclosed in Figure 2, we provide shoes one above and one below the pulley 23, the shoes being swivelled on the front ends of rods 5! extending through spring holding boxes 52 enclosing springs 53 which thrust against enlarged portions 54 on the rods 5i and move to the right and stop. slide 20 to the right, he will simply leave it there,

react against rear closures 55 of the boxes 52. The boxes 52 are formed on the ends of arms 56 which, as clearly shown, are fastened to and extend forwardly from the posts 22.

Referring now to Figure 4, the tool slide 20 may be accurately positioned with respect to the headstock l5, as by means of an abutment 60 on the tool slide engaging an adjustable screw 6| projecting from a slide bracket 62 which may be clamped at any position along the front way I6 by means of a screw 63.

The machine may be and preferably is provided with power means to move the tool slide 20 towards and from the headstock l5. Referring now to Figure 1, extending downwardly from the tool slide 20 into the opening 41 between the ways it is an integral depending portion 55 of the slide 20. To this is attached a piston rod 56, which extends horizontally to the outside of the base ID. Fastened to the outside of the base I is a cylinder 61 containing a piston 63 on the end of the piston rod 65.

In the base ll] of the machine is located a reservoir 10. In the base I0 is likewise located a fluid pump H driven in any suitable manner, not shown. Pump H is connected to a relief valve 12, and both of the pump and the relief valve have pipes leading to the reservoir 15. This constitutes well known fluid pressure mechanism (preferably pumping oil) to establish a predetermined pressure in a pipe 13 leading to a slide valve 14 of a well known type. The valve 14 is connected by pipes l and 16 to opposite ends of the cylinder 61, and a return pipe I! returns fiuid to the reservoir 10. A lever 89 is provided to control the slide 20.

The foregoing constitutes a convenient means for moving the slide 20 to and fro to permit rings to be changed in the chuck l8, and to hold the slide 20 against the back pressure of the springs 53, but any other suitable mechanism may be employed for the purpose, such as a hand wheel and rack and gear, or screw and nut.

To operate the machine the operator, finding the slide 20 to the left will move the valve lever 80 to the right, which will cause the slide 25 to Or, finding the but in any event the operator inserts a ring 9 in the jaw chuck I8, starts the motor H, and then throws the lever 80 to the left. The slide thereupon moves in and the belt 45 contacts the ring 9 with a yielding pressure. The shoes 50, being swivelled, cause the belt 45 to conform to the surface being polished or lapped. When the polishing, lapping, or finishing operation is complete, the operator swings the lever 81] to the right, which moves the slide 20 outwardly, stops the motor ll, removes the finished ring 9 from the chuck l8, and replaces it with an unfinished one. The motor Il may be controlled by a switch 8|.

It will be noted that the shoes 5! are in spaced relation on either side of the pulley 23 and hence two belt portions contact the ring 9 on opposite ends of a diameter. Due to the rotation of the ring, the polishing lines are neither radial nor concentric, but are at an angle between these two limits, depending upon the relative speeds of the belt 45 and of the surface of the ring 9 due to its angular velocity. It is desirable to provide rheostats for the motors 32 and H to adjust this angle and also to vary the actual speeds of the belt and ring. It is further to be noted that, whereas the belt moves in a straight line (projected) in the plane of the annulus of the ring, the ring itself moves perpendicular to this line in two different directions on opposite sides of its diameter. Therefore, the polishing lines cross, and this breaks up the abrading action to produce a fine polishing or lapping.

It will thus be seen that there has been provided by this invention apparatus in which the various objects hereinabove set forth together with many thoroughly practical advantages are successfully achieved. As many possible embodiments may be made of the above invention and as many changes might be made in the embodiment above set forth, it is to be understood that all matter hereinbefore set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

We claim:

1. An apparatus for performing an abrading action upon a ring-shaped portion of a ring work-piece, comprising a rotary support for holding the ring work-piece to expose the ring-like portion thereof, a frame having spaced pulley means supporting an abrasive belt with a portion intermediate of the pulley means exposed toward said work-piece support and the ring portion of the work-piece supported thereby and with said intermediate portion of the belt extending along the plane of a chord of said work-piece, means mounting said support and said frame for relative movement in the general direction of the axis of said rotary support to bring said abrasive belt and work-piece into or out of operative engagement, a pulley carried by said frame and engaging said intermediate belt portion at a point intermediate the ends of said chord whereby, upon relative movement between said support and said frame to bring said belt and work-piece into operative engagement with the belt engaging the work-piece at substantially the ends of said chord, said pulley may be at least partially accommodated in the space within said ring work-piece; means driving said rotary support to give said ring-like portion of the work-piece a surface speed high enough for abrading action relative to said belt, means for driving said belt at a surface speed high enough for abrading action relative to the work-piece, whereby the abrading action is in a general direction that is a composite of the rotary movement of the ring portion and of the straight-line motion of the belt and means for determining the pressure of engagement of the belt at substantially the ends of said chord with the work-piece.

2. An apparatus for performing an abrading action upon a ring-shaped portion of a ring work-piece, comprising a rotary support for holding the ring work-piece to expose the ring-like portion thereof, a frame having two springpressed shoes spaced apart by substantially the length of a chord of said ring-like portion of the work-piece and pulley means carried by said frame and supporting and guiding an abrasive belt that passes over said shoes, means for driving said belt and means for driving said rotary support, and means for effecting relative movement of said support and said frame in the general direction of the axis of said support to bring said belt and work-piece into operative engagement at opposed ends of said chord and includ-' ing means for determining the pressure with which the springs of said shoes press the belt into engagement with the work-piece.

3. An apparatus for performing an abrading operation upon the substantially conical end face of a ring work-piece, comprising a frame having spaced pulley means for supporting an abrasive belt and a pulley engaging an intermediate reach of the belt to present portions of the belt to either side of said pulley that make an angle commensurate with the angle of said conical end face of the work-piece, a rotary support for holding said work-piece with said conical face exposed, means mounting said support and said frame for relative movement in an axial direction with the apex of said two belt portions substantially in line with the axis of said support to effect engagement between said portions of the belt and said conical face at the ends of substantially a chord of said ring work-piece, two shoes for pressing said belt portions against said conical face, and means mounting said shoes from said frame and comprising an articulated connection for each shoe for self-adjustment thereof to the angle of said face and thereby press its belt portion substantially uniformly throughout the area of said face engaged by the belt.

HERBERT S. INDGE.

GEORGE E. HULBERT. 

